The invention relates to medical devices for introducing catheters or the like into blood vessels of the body.
Catheter introducers provide a reusable conduit for the passage of catheters and other medical devices, e.g., guidewires, through the body flesh into blood vessels or other body passageways. The catheter introducer is initially inserted into the blood vessel through the use of an introducer assembly.
Introducer assemblies are well known in the prior art. U.S. Pat. No. 5,098,392 granted to K. Amplatz et al. on Mar. 24, 1992 discloses such an introducer assembly comprising (1) an introducer element consisting of an elongated tubular member defining an introducer sheath and an introducer hub disposed at the proximal end of the introducer sheath which further defines an introducer conduit along a longitudinal axis, and (2) a dilation element consisting of an elongated tubular member defining a dilator having a tapered distal end portion and a dilator hub disposed at the proximal end of the dilator, which is sized so that the dilator may be inserted through the conduit of the introducer hub and introducer sheath and that the dilator tapered distal portion extends beyond the introducer sheath distal end.
Prior to the use of the introducer assembly, a needle is inserted through the body flesh and into a blood vessel, and a guidewire is inserted into the blood vessel through the center passage of the needle. The needle is then removed leaving the guidewire in place. The introducer assembly is then inserted over the guidewire such that the tapered distal portion of the dilator acts to gradually expand the puncture opening to ease the passage of the introducer sheath into the blood vessel. After the introducer sheath has been inserted to a desired depth within the blood vessel, the dilator element is removed from within the introducer element.
During the initial insertion of the introducer assembly, the body's resistance to the expansion of the puncture opening exerts forces on the distal portion of the dilator tending to push the dilator distal end rearwardly in the proximal direction into the introducer sheath. In order to ensure that the tapered distal portion of the dilator remains extended beyond the blunt distal end of the introducer sheath during the initial insertion of the introducer assembly, the dilator hub is releasably connected to the introducer hub.
In addition to introducer/dilator assemblies, other catheter assemblies include the combination of an introducer sheath with obturators, sterile sleeves, Tuohy-Borst fittings and the like.
Several means for releasably connecting the introducer hub and the hub of the other component of the assembly, e.g. the dilator hub, are known in the prior art. Unfortunately, with these prior art designs, the interconnected hubs are prone to becoming accidently disengaged.
A prior art means for releasably connecting the dilator hub and introducer hub comprises rotatably engaging studs and complementary slots associated with the dilator and introducer hubs. Seberg U.S. Pat. No. 4,192,305 discloses a catheter placement assembly having a needle and lumen wherein the needle and lumen are mechanically engaged by complementary means associated with the needle and lumen hubs, such as tabs associated with one hub and slots associated with the other hub. U.S. Pat. No. 4,946,443 granted to L. Hauser et al. on Aug. 7, 1990 discloses a catheter assembly having a releasable connecting means consisting of a pin or stud associated with one hub that is received by a slot associated with the other hub. Medical assemblies having releasable connecting means of the pin-and-slot type are also disclosed in Morrison U.S. Pat. No. 4,609,370; Burney et al. U.S. Pat. No. 4,986,814; and Patel U.S. Pat. No. 3,860,006. These types of rotatably engaging releasable connecting means do not have a stop means for securely locking the pin within the slot and, therefore, are prone to accidental disengagement through the inadvertent rotation of the dilator hub.
Other prior art releasable connecting means do not suggest a means for inhibiting the rotational disengagement of the introducer and dilator hubs. For instance, Amplatz et al. U.S. Pat. No. 5,098,393 discloses that the dilator hub and introducer hub may be releasably connected by an axially engaging snap fit or friction fit connection. An axially aligned snap fit connection of the type disclosed in Amplatz et al. U.S. Pat. No. 5,098,393 is prone to accidental disengagement through the inadvertent application of a transverse force to the proximal end of the dilator hub. Moreover, while the axial alignment of the dilator and introducer hubs is maintained with such a releasable connection, rotational movement between the dilator and introducer hubs is permitted.
Upon an accidental disengagement of the dilator hub and introducer hub during the initial insertion of the introducer assembly, the tapered distal end of dilator would migrate proximally into the introducer sheath and the blunt distal end of the introducer sheath may be forced into the blood vessel. In that event, trauma to the blood vessel and body flesh surrounding the puncture site could result. Such trauma may result in the procedure being re-initiated at another location along the blood vessel or being abandoned altogether. Accidental disengagement of an obturator can result in kinking of the introducer sheath thus preventing further use of the sheath and requiring replacement with a new sheath. Similarly, disengagement of a sterile sleeve from the introducer sheath will compromise the required sterile environment. Further, disengagement of the Tuohy-Borst fitting from the introducer sheath can cause the catheter, which is received by the fitting and within the introducer, to move from its desired position in the patient.
Accordingly, it is an object of the present invention to provide a catheter assembly with an improved rotatably engaging releasable interlock connection between the hubs of the assembly components which minimizes, or preferably eliminates, the risk of accidental disengagement of both the axial and rotational alignment of the hubs.